A clean environment is essential for human health and well-being. However, the interactions between the environment and human health are extremely complex and difficult to assess. This makes the use of the precautionary principle extremely useful. The best known health impacts refer to ambient air pollution, poor water quality and poor hygiene. Much less is known about the health impacts of hazardous chemicals. Noise is an emerging health and environmental issue. Climate change, ozone depletion, biodiversity loss and soil degradation can also affect human health.